Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft affixed to the motor rotor. In a hermetic compressor, the bottom of the hermetic shell normally contains an oil sump for lubricating and cooling purposes.
Scroll compressors depend upon a number of seals to be created to define the moving or successive chambers. One type of seals which must be created are the seals between opposed flank surfaces of the wraps. These flank seals are created adjacent to the outer suction port and travel radially inward along the flank surface due to the orbiting movement of one scroll with respect to the other scroll. Additional sealing is required between the end plate of one scroll and the tip of the wrap of the other scroll. These tip seals have been the subject of numerous designs and developments in the scroll compressor field.
One solution to the creation of tip seals has been to machine a groove in the end surface of the wrap and insert a sealing member which can be biased away from the wrap and towards the end plate of the opposite scroll. Unfortunately, due to the complex shape of the wraps themselves, the machining of the groove, the manufacture of the sealing member and the assembly of these components, the costs associated with incorporating tip seals are excessive. Although expensive, tip seals have performed satisfactorily in creating the required sealing between the tip of the wrap and the opposing end plate.
Other designs for scroll compressors have incorporated axial biasing of one scroll with respect to the opposing scroll. The axial biasing operates to urge the tips of the scroll members against their opposing end plate in order to enhance the sealing at the tip of the wrap. The biasing of one scroll member with respect to the opposing scroll member in conjunction with dimensional control of the scroll members themselves has allowed scroll compressors to be manufactured without separate sealing members between the tip of the wrap and the opposing end plate.
The present invention provides the art with a scroll compressor which eliminates a significant amount of machining of the end plate. The end plates of the scroll members are only machined in the area which interface with the opposing scroll wrap. The remaining surface area of the end plates is left unmachined with the height of the scroll wraps being sufficient to avoid undesired contact between the two scrolls. In this manner, the scroll wraps support the entire biasing load between the two scrolls.
Other advantages and objects of the present invention will become apparent to those skilled in the art from the subsequent detailed description, appended claims and drawings.